1. Field of the Invention
The present invention relates to a locking apparatus for a shift lever of an automatic transmission, and particularly, to a locking apparatus for a shift lever of an automatic transmission, in which the locking of the shift lever can be released manually.
2. Description of the Related Art
The shift lever of the automatic transmission is of a construction in which the shift lever is brought out of engagement with a detent plate by the movement in the shift lever axial direction of a detent pin mounted on the shift lever, thereby permitting a shifting operation. A known shift lever locking apparatus in which the shift lever can be operated only under a specific condition such as during a braking operation or the like including one in which the detent pin is restrained by a solenoid (see Japanese Utility Model Application Laid open No. 176253/84). In such a shift lever locking apparatus, when the shift lever is in a parking range (P range), engagement of the detent pin with a plunger of the solenoid causes the shifting movement of the shift lever to be restrained, while enabling the withdrawal of a key from an ignition key-insertion cylinder. Therefore, in a state in which the key has been withdrawn from the cylinder (i.e., in an engine-stopped state), the movement of the detent pin is prevented by the solenoid, and the shift lever is fixed in the P range. If an ignition switch is in an "on" position, the solenoid is excited, so that the solenoid plunger is pulled into the solenoid to permit the movement of the detent pin, thereby ensuring that the shift lever can be freely shifted.
Apart from such an apparatus, there is also known a locking apparatus for a shift lever, which is designed so that the solenoid is energized when a braking operation is conducted.
In this locking apparatus for a shift lever of an automatic transmission, the provision of a manual releasing member for forcibly moving the solenoid plunger manually to release the restraint of the shift lever ensures that the vehicle can be moved even when there is trouble with the electrical system of a vehicle or when the vehicle is being repaired under a condition where the power source has been disconnected. However, it is desirable that the manual releasing member cannot be operated except when necessary.